The CHRONICLE Study of US Adults with Subspecialist-Treated Severe Asthma: Objectives, Design, and Initial Results

Pragmat Obs Res. 2020 Jul 16;11:77-90. doi: 10.2147/POR.S251120. eCollection 2020.


Background: Approximately 5-10% of patients with asthma have severe disease. High-quality real-world studies are needed to identify areas for improved management.

Objective: Aligned with the International Severe Asthma Registry, the CHRONICLE study ( NCT03373045) was developed to address this need in the US.

Study design: Learnings from prior studies were applied to develop a real-world, prospective, noninterventional study of US patients with confirmed severe asthma who are treated by subspecialist physicians and require biologic or maintenance systemic immunosuppressant therapy or who are uncontrolled by high-dosage inhaled corticosteroids and additional controllers. Target enrollment is 4000 patients, with patient observation for ≥3 years. A geographically diverse sample of allergist/immunologist and pulmonologist sites approach all eligible patients under their care and report patient characteristics, treatment, and health outcomes every 6 months. Patients complete online surveys every 1-6 months.

Initial results: From February 2018 to February 2019, 102 sites screened 1428 eligible patients; 936 patients enrolled. Study sites (40% allergist/immunologist, 42% pulmonologist, 18% both) were similar to other US asthma subspecialist samples. Enrolled patients were 67% female with median ages at enrollment and diagnosis of 55 (range: 18-89) and 26 (0-80) years, respectively. Median body mass index was 31 kg/m2; 3% and 29% were current or former smokers, respectively, and >60% reported ≥1 exacerbation in the prior year and suboptimal symptom control.

Conclusion: CHRONICLE will provide high-quality provider- and patient-reported data from a large, real-world cohort of US adults with subspecialist-treated severe asthma.

Keywords: allergists; asthma exacerbations; biologic therapy; longitudinal studies; pulmonologists.

Associated data


Grant support

This work was supported by and the CHRONICLE study is funded by AstraZeneca.